Weird Mouse Look Sensitivity Issues

[Prahadigm24]

Hey,

I've installed Win7 and now I have a problem which hadn't been there before (Vista):

EQ fullscreen works fine. Unfortunately I need the windowed mode, which also works fine, unless I open a browser window (Firefox) next to EQ. As soon as the browser process is started, the mouselook sensitivity in EQ drops massively. It's actually unplayable until I close the browser again. This seems to be weird, because the mouse speed remains unaffected both in EQ and in Windows. But the mouselook sensitivity in EQ is messed up and I can't turn my character around anymore.

Does anybody have an idea how Firefox can cause this? Any help would be really appreciated, this is very annoying.